Ketene diphenyl

Diphenyl-keten wird durch Lithiumalanat zum Diphenyl-acelaldehyd3 (93% d.Th.) re-duziert ... 

The structure of the adduct formed from triethyl phosphite and diphenyl keten, which has been the subject of some speculation, is now shown to be (51). ... 

The product profile thus reveals impressive parallels with the reaction of diphenyl-ketene, the carbon analogue of 9, with (p-methoxybenzal)acetophenone, in which, again under thermal conditions, both cycloadditions and fragmentation of the four-membered ring product25) occur. Overall, the rate or rearrangement 7- 9 appears to be more favorable by the thermal route than by the photochemical pathway. 

A viscous red residue always remains in the distilling flask, necessitating superheating to remove the last traces of diphenyl-ketene. 

Benzyliden-amino)-l, 3,4-oxadiazole reagieren als Azadiene mit Diphenyl-keten unter Cycloaddition zu 2,7-Diaryl-6,6-diphenyl-5-oxo-6,7-dihydro-5H-685 ... 

The nucleophilic 7V,ALdiethyI-l-propynamine adds across the C=C bond of 31 at 20° C to yield the adduct 187, whereas the electrophilic diphenyl-ketene adds across the N=N bond at -8°C to give 188 (97%).167 This difference in behavior finds a parallel in the Diels-AIder reactions (Section IV.E.l). 

Cycloaddition of diphenyl ketene with benzoquinone diimides (44) gives quinoxalinones of type 45.45 Analogous additions of olefins lead to tetrahydroquinoxalines these reactions are classified as Diels-Alder additions with inverse electronic demand. 

Isothiazoles are reported to yield lactams (395) on reaction with diphenyl ketene (85BSB149). 

Diphenyldiazomethane reacts with 2,6-diphenylpyran-4-thione (58JA6312) and diphenyl-ketene with the corresponding pyranone (l 1LA(384)38) to give the substituted methylenepyran (Scheme 25). 

The reduction of a-amino mixed anhydrides with lithium tri-/ert-butoxyaluminum hydride in THF at —70 °C is a very efficient method for synthesis of amino aldehydes (Table 9). 551 Three approaches were taken for the reduction of a-amino mixed anhydrides. 55 The first approach reduced Boc-Ala-OC02Et with lithium tri-terf-butoxyaluminum hydride was unsuccessful due to intramolecular rearrangements that gave Boc-Ala-OEt in addition to the Boc-Ala-H. The second approach involved reduction of diphenylacetic anhydride derivatives, which were prepared from Boc amino acids and diphenyl ketene, gave a diphenylacetic acid byproduct that was very difficult to remove unless the aldehyde was converted into its semicarbazone and separated chromatographically yields were 51-69%. The last and... 

The final step in the Pd-catalyzed reaction of diphenyl ketenes and allyl acetates (Section 3.3.2.3.1) involves 0-H elimination to generate a diene (equation 126).264... 

Ketenes are rarely isolated as they dimerise easily. Ketene itself 2 gives the lactone 5 but dimethylketene 6 gives the diketone 7. Other ketenes may give either type of dimer. Only a few ketenes, such as diphenyl ketene, are normally isolated. 

Diphenyl ketene reacts with 39 to yield what has been described as a metal-anchored olefin complex (40) (109). The latter contains a diphenyl ketene ligand which is tj2-C,0 (a metallocyclopropene) -bonded to the (r)-C5H5)2Ti unit. Upon treatment of 40 with protic acids, carbon mon-... 

In contrast to reaction (5-33), the rate for the eyeloaddition reaction of diphenyl-ketene to n-butyl vinyl ether shows a mueh smaller solvent dependence cf. Eq. (5-34) [100]. 

Staudinger, H. Ketenes. VIII. Preparation of Quinoidal Hydrocarbons from Diphenyl Ketene. Ber. 1908,41, 1355-1363. 

CYCLOADDITIONS f-Butyicyanoketene. a-Chloro-N-cyclohexylpropanaldoxime. Chlorosulfonyl isocyanate. Dichloroke-tene. Dimethyl acetylenedicarboxylate. Diphenyl ketene, 2-Methoxyallyl bromide. 2-Methoxy-6-methyl-l,4,3,5-oxathiadia-zine 4,4-dioxide. Oxygen, singlet. 4-Phen-yl-l,2,4-triazoline-3,5-dione. Silver fluoro-borate. Trimethylsilyldiazomethane. 

The reaction of diphenyldiazomethane with l,2-dithiole-3-thiones gave the same compounds 150 as those isolated from the reaction with diphenyl-ketene.214... 

A number of C-C coupling reactions involving the activation of aromatic C-H bonds have been reported with the rhodium clusters Rh4(CO)12 and Rh6(CO)16 as catalysts. Thus, benzene can be reacted with diphenyl ketene, according to... 

Oxalyl chloride (ethanedioyl dichioride) can be an effective, alternative, chloroformylating agent to phosgene. The reaction of oxalyl chloride with diphenyl ketene, for example, proceeds under milder conditions than with phosgene to give the identical organic product [1938] ... 

By reaction with diphenyl ketene, the N—N bond of the diaziridine is broken. Depending on the substituents at the ring carbon either the ketene aminal 127 or the azetidine 128 is obtained. 

Isothiazoles are reported to yield the lactam (101) on reaction with diphenyl ketene <85BSB149>. Ethyne dicarboxylate esters add to 2,1-benzisothiazole to generate quinoline esters (102), and benzyne reacts to yield aeridine <83H(20)489, 88JCS(Pl)2l4l>. 2-Methyl-2,l-benzisothiazolin-3-thione with acetylene esters forms 2-iminobenzoquinone methides (103), which dimerize to give diazocines (104) or further react with the ethyne ester to yield diadducts (105). The initial adduct formed with phenylethyne and 2-methyl-2,l-benzisothiazolin-3-thione rearranges to produce l,2-dithiole[3,26]... 

Photochemical cycloaddition has been reported for the dione (248). Irradiation of this compound in the presence of cyclopentadiene affords the adduct (249). Similar adducts. (250) and (251) respectively, are formed when indene and cyclopentene are used as the alkenes. In contrast to the above when six membered ring alkenes such as cyclohexa-1,3-diene and dihydropyran are used cycloaddition occurs at the ring double bond to yield the adducts (252) and (253) respectively. Several examples of the thermal and/or photochemical addition of diphenyl ketene and p-tolyl diphenylketimine to heterocyclic 1,2-diones has been reported. One example of the reaction is that of the... 

OLEFIN ADDITIONS Benzenesulfonyl azide. Chlorosulfonyl isocyanate. Chiom-ous chloride. Cyanamlde. Dichloroketene. Dinitrogen tetroxide-Iodine. Diphenyl-ketene. Ethoxyketene. Fluoroxytrifluoro-methane. Iodine. Iodine azide. Iodine isocyanate. Iodobenzene dichloride. Mercuric azide. Nitrosyl chloride. Nitrosyl fluoride. Nitryl iodide. Potassium f-but-oxide-Bromoform (dibromocarbene). 

Fig. 2.49. The [3 + 2] cycloaddition product formed from the reaction of [Re(0)3(PhTp)] with diphenyl ketene.

An aadoazole reacts exothermally with diphenyl ketene, and nitrogen is eliminated. 

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